Pin pyo3 dependency in example_tomlgen/setup.cfg

Author: Martin Larralde

example_tomlgen/setup.cfg

@@ -10,7 +10,7 @@ zip_safe = false
 create_workspace = true
 
 [tomlgen_rust.dependencies]
-pyo3 = { git = "https://github.com/PyO3/pyo3", features = ["extension-module"] }
+pyo3 = { version = "0.5.0-alpha.3", features = ["extension-module"] }
 
 [tomlgen_rust.dependencies.hello-english]
 english-lint = "*"